<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Title</title>
</head>
<body>
<script>
	function add(a, b=1) {
		return a + b;
	}
	console.log(add(10));
	console.log(add(10, 2));

	function fun(...values) {
		for (let i = 0; i < values.length; i++) {
			console.log(values[i]);
		}
		console.log('------------')
	}
	fun(1, 2) //2
	fun(1, 2, 3, 4) //4
</script>
</body>
</html>